(a) Technical Field
The present invention relates to an apparatus and method for processing a signal using a single correlator and, more particularly, to technology related to a Global Positioning System (GPS) whose speed and performance can be ensured even when tracking a plurality of satellite signals using a single correlator.
(b) Background Art
A Global Positioning System (GPS) is a position measurement system providing position information using satellites in geostationary orbits. The GPS was originally developed for military purposes, but has been widely used in various fields since the year 2000 when the intentional adding of noise known as Selective Availability (SA) was removed. The GPS uses the same frequency band in different codes by the code division multiple access (CDMA) method.
In the GPS, a GPS receiver capable of measuring three-dimensional position and time using at least four satellites comprises an antenna for receiving satellite signals, an RF unit for demodulating a necessary signal from the satellite signals received by the antenna, a signal processor for down-converting the signal passing through the RF unit to baseband, and a user interface. Research aimed at further developing the signal processor down-converting a received signal to baseband continues to progress in the direction of increased channels and reduced size, and this trend will continue.
The core of the signal processor of the GPS receiver is a correlator, and various performance indexes of the GPS are set according to the structure of the correlator. The GPS correlator receives a signal passing through an RF terminal, down-converts the received signal into a baseband signal, and despreads the baseband signal to restore data. For example, the satellite signal is down-converted into an intermediate frequency at the RF terminal, quantized to 2 bits, and then input to the correlator. The correlator down-converts the input signal into a baseband signal, multiplies the baseband signal by a pseudo noise code, and integrates the resulting signal. As shown in FIG. 1, the GPS receiver includes 12 to 16 correlators such that one correlator is assigned to each satellite to extract one measured value.
In the case where the plurality of correlators are used in the GPS receiver, signal acquisition speed is high but so is power consumption, and it is necessary to increase the integration of the chip. Moreover, since each correlator possesses a fixed signal tracking channel, it occupies hardware resources, and thus resource efficiency decreases due to the fixed structure.
Moreover, the correlator of the conventional GPS receiver operates repeatedly each time sampling is performed in synchronization with a sampling frequency. However, since various components capable of operating at high speed have been developed, it is possible to implement a correlator capable of operating at a speed several to several tens of times faster than the existing sampling frequency. Therefore, a plan for implementing and effectively utilizing a correlator capable of operating at high speed is urgently required.